Medical image processing apparatus and medical image processing method

ABSTRACT

There is provided a medical image processing apparatus which includes a first extraction unit configured to extract coronary arteries depicted in images of a plurality of time phases relating to the heart, and to extract at least one stenosed part depicted in each coronary artery; a calculation unit configured to calculate a pressure gradient of each of the extracted coronary arteries, based on tissue blood flow volumes of the coronary arteries; a second extraction unit configured to extract an ischemic region depicted in the images; and a specifying unit configured to specify a responsible blood vessel of the ischemic region by referring to a dominance map, in which each of the extracted coronary arteries and a dominance territory are associated, for the extracted ischemic region, and to specify a responsible stenosis, based on the pressure gradient corresponding to a stenosed part in the specified responsible blood vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCT Application No.PCT/JP2013/082278, filed Nov. 29, 2013 and based upon and claiming thebenefits of priority from Japanese Patent Applications No. 2013-248490,filed Nov. 29, 2013, No. 2012-263565, filed Nov. 30, 2012, and No.2012-263566, filed Nov. 30, 2012, the entire contents of all of whichare incorporated herein by reference.

FIELD

Embodiments of the present invention relate to a medical imageprocessing apparatus or a medical image processing method.

BACKGROUND

In general, in ischemic heart diseases, a blood flow to the cardiacmuscle is hindered due to occlusion, stenosis, etc. of a coronaryartery, and the supply of blood becomes deficient or stops, leading to afailure of the heart. A symptom is a sensation of pain or compressionmainly in the precordia or, in some cases, in the left arm or in theback. Therapeutic methods for patients with ischemic heart diseases aregenerally classified into bypass surgery, PCI (catheter surgery), andpharmacotherapy.

The bypass surgery is a therapeutic method in which, as illustrated inFIG. 20, some other blood vessel is connected to a blood vessel which isstenosed or occluded, thereby causing more blood to flow through thisconnected blood vessel to a region in which ischemia occurs.

PCI is a therapeutic method in which, as illustrated in FIG. 21 and FIG.22, a therapeutic instrument with a thin tubular structure is directlyinserted in a blood vessel in which occlusion or stenosis occurs,thereby forcibly expanding the blood vessel.

The pharmacotherapy is a therapeutic method for improving ischemia ofthe heart, or preventing formation of a thrombus.

There is known FFR (Fractional Flow Reserve) as an index which a doctorrefers to when selecting any one of these three therapeutic methods.

In general, assessment of the degree of progress of stenosis is carriedout by directly inserting a pressure wire into a blood vessel. Thepressure wire is inserted, as illustrated in FIG. 23, and pressuresP_(in) and P_(out) at regions in front of and behind a stenosed part aremeasured.

Here, the FFR is defined by P_(out)/P_(in). If this value is lower than0.8, the doctor selects the PCI as the therapeutic method. If this valueis higher than 0.8, the doctor selects pharmacotherapy as thetherapeutic method. However, since the measurement of the pressuresP_(in) and P_(out) with use of the pressure wire is invasive, there is ademand for a non-invasive measuring method and FFR estimation method.

This being the case, in recent years, a simulation-based FFR estimationmethod using fluid analysis has been devised. An existing simulation isa simulation using 3D images. In the basic concept of such asimulation-based FFR estimation method, the shape of a blood vessel,which is obtained from modality, and physical parameters, such as aviscosity value, etc. of blood, etc., are used as inputs, and FFR isestimated (calculated) by using a Navier-Stokes equation which is usedin, e.g. CFD (Computational Fluid Dynamics).

A problem with such 3D simulation is that a great deal of calculationtime is required. Thus, such a problem arises that time is also neededuntil selecting a therapeutical method by using the FFR, and the 3Dsimulation is not suitable when there is no time to lose. As a measurefor an improvement, there is a method in which the time needed forsimulation is greatly reduced by executing 2D approximation of thesimulation that uses 3D images.

Thereby, it becomes possible to quickly calculate FFR on the basis ofsimulation, and the doctor can use FFR as an effective index.

At present, however, it is not possible to assess the causalrelationship between an ischemic cardiac muscle and a stenosed part tobe treated, or to make risk assessment. Specifically, the FFR fails tobe properly reflected on the assessment of the causal relationshipbetween an ischemic cardiac muscle and a stenosed part to be treated,and on the risk assessment. Judgment as to, for example, which stenosedpart is to be treated with top priority depends greatly on the empiricalrule of doctors. Thus, such a problem arises that there is a concern ofoccurrence of a human error, such as unnecessary treatment or anoversight.

In addition, for example, in a coronary artery which contributes tomyocardial infarction, since the blood flow volume and pressuredecrease, the FFR apparently increases. Thus, despite such a serioussymptom as myocardial infarction having been caused, the FFR isapparently high. In this case, too, such a problem arises that there isa concern of occurrence of a human error, such as an oversight of asymptom, or erroneous selection of a therapeutic method.

The object is to provide a medical image processing apparatus which canreduce the possibility of a human error.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a configuration example of amedical image processing system including a medical image processingapparatus according to a first embodiment.

FIG. 2 is a schematic view illustrating an example of a territory mapwhich is stored in a territory map storage unit according to the firstembodiment.

FIG. 3 is a flowchart illustrating an example of the operation of themedical image processing apparatus according to the first embodiment.

FIG. 4 is a schematic view illustrating an example of an analysis resultby a coronary artery analysis unit according to the first embodiment.

FIG. 5 is a schematic view illustrating an example of an analysis resultby a cardiac muscle analysis unit according to the first embodiment.

FIG. 6 is a schematic view illustrating an example of athree-dimensional image of a responsible blood vessel which is displayedby a display unit according the embodiment.

FIG. 7 is a schematic view illustrating an example of a two-dimensionalimage of a responsible blood vessel which is displayed by the displayunit according the first embodiment.

FIG. 8A is a schematic view illustrating an example of a two-dimensionalimage of a responsible blood vessel which is displayed by the displayunit according the first embodiment, the two-dimensional imagesuggesting the degree of priority of treatment.

FIG. 8B is a schematic view illustrating an example of a two-dimensionalimage of a responsible blood vessel which is displayed by the displayunit according the first embodiment, the two-dimensional imagesuggesting the degree of priority of treatment.

FIG. 9 is a schematic view illustrating an example of a two-dimensionalimage of a responsible blood vessel which is displayed by the displayunit according the first embodiment, the two-dimensional imagesuggesting the presence of a collateral vessel.

FIG. 10 is a schematic view illustrating an example of a two-dimensionalimage of a responsible blood vessel which is displayed by the displayunit according the first embodiment, the two-dimensional imagesuggesting the size of a catheter/stent.

FIG. 11 is a schematic view illustrating a configuration example of amedical imaging system including a medical image processing apparatusaccording to a second embodiment.

FIG. 12 is a flowchart illustrating an example of the operation of themedical image processing apparatus according to the second embodiment.

FIG. 13 is a schematic view illustrating an example of a markerrepresenting a contour of an infarction responsible blood vessel, whichis generated by a marker generator according to the second embodiment.

FIG. 14 is a schematic view illustrating an example of a markerrepresenting a transition of FFR values, which is generated by themarker generator according to the second embodiment.

FIG. 15 is a schematic view illustrating an example of a two-dimensionalimage of an infarction responsible blood vessel which is displayed by adisplay unit according the second embodiment.

FIG. 16 is a schematic view illustrating an example of athree-dimensional image of an infarction responsible blood vessel whichis displayed by the display unit according the second embodiment.

FIG. 17 is a flowchart illustrating another example of the operation ofthe medical image processing apparatus according to the secondembodiment.

FIG. 18 is a flowchart illustrating an example of the operation of amedical image processing apparatus according to a third embodiment.

FIG. 19 is a schematic view illustrating an example of athree-dimensional image of an infarction responsible blood vessel whichis displayed by a display unit according the third embodiment.

FIG. 20 is a schematic view for explaining the principle of bypasssurgery.

FIG. 21 is a schematic view for explaining the principle of a catheteroperation on a blood vessel stenosis.

FIG. 22 is a schematic view for explaining the principle of a ballooncatheter operation.

FIG. 23 is a schematic view for explaining an insertion method of apressure wire into a coronary artery.

DETAILED DESCRIPTION First Embodiment

A medical image processing apparatus disclosed by this embodimentcomprises a first extraction unit, a calculation unit, a secondextraction unit, a specifying unit and a display. The first extractionunit is implemented by processing circuitry and configured to extract aplurality of coronary arteries depicted in data of images of a pluralityof time phases relating to the heart, and to extract at least onestenosed part depicted in each of the extracted coronary arteries. Thecalculation unit is implemented by processing circuitry and configuredto calculate a pressure gradient of each of the extracted coronaryarteries, based on tissue blood flow volumes of the plurality ofextracted coronary arteries. The second extraction unit is implementedby processing circuitry and configured to extract an ischemic regiondepicted in the images. The specifying unit is implemented by processingcircuitry and configured to specify a responsible blood vessel of theischemic region by referring to a dominance map, in which each of theextracted coronary arteries and a dominance territory are associated,for the extracted ischemic region, and to specify a responsiblestenosis, based on the pressure gradient corresponding to a stenosedpart in the specified responsible blood vessel. The display isconfigured to display an image in which the specified responsiblestenosis is depicted, together with information indicative of theresponsible stenosis.

FIG. 1 is a schematic view illustrating a configuration example of amedical image processing system including a medical image processingapparatus according to a first embodiment. FIG. 2 is a schematic viewillustrating an example of a territory map which is stored in aterritory map storage unit according to the embodiment. A medical imageprocessing system 1 illustrated in FIG. 1 is a system in which a medicalimage processing apparatus 10, a CT (Computed Tomography) apparatus 20and a PACS (Picture Archiving and Communication System) 30 arecommunicably connected via a network 40 such as a LAN (Local AreaNetwork) or a public electronic communication network. Thus, the medicalimage processing apparatus 10 is provided with a communication interface103 which enables communication with the CT apparatus 20 and PACS 50.

As illustrated in FIG. 1, the medical image processing apparatus 10includes an image storage unit 101, a territory map storage unit 102,the communication interface 103, a controller 104, a heart regionextraction unit 105, a cardiac muscle analysis unit 106, a coronaryartery analysis unit 107, a responsible blood vessel specifying unit108, an FFR calculator 109, a responsible stenosis specifying unit 110,a marker generator 111, and a display unit (a display) 112. Hereinafter,the functions of the respective components 101 to 112, which constitutethe medical image processing apparatus 10, will be described in detail.It is noted that, the controller 104, the heart region extraction unit105, the cardiac muscle analysis unit 106, the coronary artery analysisunit 107, the responsible blood vessel specifying unit 108, the FFRcalculator 109, the responsible stenosis specifying unit 110 or themarker generator 111 is realized by at least one processing circuitryand at least one memory.

The image storage unit 101 is a storage device, such as memory, whichstores time-series three-dimensional contrast-enhanced CT image data(hereinafter, simply referred to as “volume data”) over a plurality oftime phases relating to a chest region including the heart of thesubject, as process images which are transmitted from the CT apparatus20 or PACS 50 under the controller 104.

The territory map storage unit 102 is a storage device, such as memory,which stores a territory map (hereinafter referred to as “territorymap”) which defines, as illustrated in FIG. 2, a relationship betweencoronary arteries and dominance territories to which nutrition issupplied by the respective coronary arteries.

The heart region extraction unit 105 extracts a heart region from thevolume data by a heart contour extraction process or the like.

The cardiac muscle analysis unit 106 extracts a cardiac muscle regionfrom the heart region extracted by the heart region extraction unit 105,for example, by a threshold process by CT values corresponding to acontrast medium concentration. In addition, the cardiac muscle analysisunit 106 executes cardiac muscle perfusion analysis, that is, generatesa time-concentration curve relating to a contrast medium with respect toeach pixel or each local part within the extracted cardiac muscleregion, and calculates, based on the time-concentration curve, thevolume of a blood flow moving during a period from flow-in to flow-outof the contrast medium with respect to each pixel or each local part.

For example, in the photography using the CT apparatus, a non-ioniccontrast medium is injected in the patient, and perfusion information ofan internal organ can be depicted from the variation of the CT values.Thus, in the CT perfusion analysis, a time-based variation of a CT image(volume data), which is composed of, for example, 512×512 pixels, ismeasured from a variation of the CT value at each pixel, and the bloodflow volume, etc. can be numerically expressed. In this manner, onecolor map representing the perfusion information (e.g. blood flowvolume) of the internal organ is generated from the CT images of pluraltime phases.

Furthermore, the cardiac muscle analysis unit 106 specifies an ischemicregion by a threshold process from a spatial distribution of thecalculated blood flow volume.

The coronary artery analysis unit 107 extracts a plurality of coronaryarteries from the heart region extracted by the heart region extractionunit 105, and further extracts at least one stenosed part from eachextracted coronary artery. Specifically, the coronary artery analysisunit 107 executes analysis of an anatomical structure of a coronaryartery and a plaque nature along a vessel center line of the coronaryartery, the inner wall of the blood vessel, etc., and extracts volumedata relating to the coronary artery, that is, extracts the coronaryartery and a stenosed part located on the inner wall of this coronaryartery. Incidentally, concrete examples of the plaque nature include alipid amount, a serum cholesterol concentration, hardness, the degree ofcalcification, the thickness of a fibrous capsule (Thin-cap), and an FFRvalue (in this embodiment, it is assumed that the FFR value iscalculated by the FFR calculator 109).

The responsible blood vessel specifying unit 108 refers to the territorymap, which is stored in the territory map storage unit 102, for theischemic region specified by the cardiac muscle analysis unit 106,thereby specifying a blood vessel (hereinafter referred to as“responsible blood vessel”) which is inherently responsible for supplyof nutrition to the ischemic region.

The FFR calculator 109 calculates, on a simulation basis, a value of FFRwhich corresponds to each stenosed part extracted by the coronary arteryanalysis unit 107. Specifically, the FFR calculator 109 firstcalculates, with respect to each stenosed part extracted by the coronaryartery analysis unit 107, a tissue blood flow volume at least at onelocation on a downstream side of each stenosed part and a tissue bloodflow volume at least at one location on an upstream side of eachstenosed part, based on the color map generated by the cardiac muscleanalysis unit 106. Then, the FFR calculator 109 calculates the FFR valueat each location including at least the stenosed part by dividing thecalculated tissue blood flow volume on the downstream side of thestenosed part by the calculated tissue blood flow volume on the upstreamside of the stenosed part. In the meantime, in the present embodiment,although the FFR calculator 109 calculates the FFR value by theabove-described calculation method, the calculation method of the FFRvalue is not limited to this. If the FFR value corresponding to eachstenosed part can be calculated, any calculation method is applicable asthe calculation method of the FFR value, which is used in the FFRcalculator 109.

The responsible stenosis specifying unit 110 specifies a stenosed part(hereinafter referred to as “responsible stenosis”) which is located onan inner wall of the responsible blood vessel specified by theresponsible blood vessel specifying unit 108, among the stenosed partsextracted by the coronary artery analysis unit 107, that is, specifies astenosed part having an FFR value of less than a threshold value, amongresponsible stenosis candidates, as the responsible stenosis.

The marker generator 111 generates data of markers which represent theresponsible blood vessel specified by the responsible blood vesselspecifying unit 108, the responsible stenosis specified by theresponsible stenosis specifying unit 110, the FFR value calculated bythe FFR calculator 109, and the responsible stenosis candidatesextracted by the coronary artery analysis unit 107. These markers aredisplayed on the display unit 112 such that the markers are superimposedon a three-dimensional image generated by rendering, etc. from thevolume data, or a two-dimensional image generated by cross-sectionconversion (Multi-Planar Reconstruction). Incidentally, the image, onwhich the markers generated by the marker generator 111 aresuperimposed, is not limited to the image derived from the volume databy the CT apparatus 20, but may be an image acquired from other modalitysuch as an X-ray diagnosis apparatus.

Referring now to schematic views of FIG. 2, and FIG. 4 to FIG. 7, and aflowchart illustrated in FIG. 3, a description is given of an example ofthe operation of the medical image processing apparatus 10 according tothe present embodiment.

To start with, upon receiving an input of time-series volume data over aplurality of time phases relating to the chest region from the CTapparatus 20 or PACS 50 via the communication interface 103, thecontroller 104 writes the volume data, the input of which was accepted,in the image storage unit 101 (step S1).

Subsequently, the heart region extraction unit 105 reads out, under thecontroller 104, volume data of a specific time phase with a relativelysmall beat, as a process image, from the image storage unit 101, andextracts a heart region from the volume data (step S2).

Next, the coronary artery analysis unit 107 executes a coronary arteryanalysis process on a target that is the heart region extracted by theheart region extraction unit 105 (step S3, S4). Specifically, thecoronary artery analysis unit 107 executes analysis of an anatomicalstructure of a coronary artery and a plaque nature along a vessel centerline of the coronary artery, the inner wall of the blood vessel, etc.,and extracts the coronary artery and a stenosed part located on theinner wall of this coronary artery. Thereafter, for example, asillustrated in FIG. 4( a) and FIG. 4( b), the coronary artery analysisunit 107 superimposes the anatomical structure of the coronary artery onthe heart morphology image, and causes the display unit 112 to displaythe superimposed image as a three-dimensional image g1 ortwo-dimensional image g2. Incidentally, the operator can arbitrarily setthe timing at which the image g1, g2 illustrated in FIG. 4( a), FIG. 4(b) is displayed on the display unit 112. Specifically, the image g1, g2may be displayed in the course of the process, or may be displayedtogether with the result of the process.

Subsequently, the cardiac muscle analysis unit 106 extracts a cardiacmuscle region from the heart region extracted by the heart regionextraction unit 105, by a threshold process by CT values correspondingto a contrast medium concentration (step S5).

Next, the cardiac muscle analysis unit 106 executes a CT perfusionanalysis process on only the extracted cardiac muscle (step S6, S7, S8).Specifically, the cardiac muscle analysis unit 106 generates atime-concentration curve relating to a contrast medium with respect toeach pixel or each local part within the extracted cardiac muscleregion. Then, the cardiac muscle analysis unit 106 calculates, based onthe time-concentration curve, the volume of a blood flow moving during aperiod from flow-in to flow-out of the contrast medium with respect toeach pixel or each local part. Thereby, for example, as illustrated inFIG. 5, a color map g3, which indicates a spatial distribution of theblood flow volume, is generated. Then, the cardiac muscle analysis unit106 specifies a region of less than a predetermined blood flow volume asan ischemic region, based on the generated color map g3, that is, thespatial distribution of the calculated blood flow volume.

Subsequently, the responsible blood vessel specifying unit 108 refers tothe dominance map, which is stored in the territory map storage unit102, as illustrated in FIG. 2, for the ischemic region specified by thecardiac muscle analysis unit 106, thereby specifying a responsible bloodvessel (step S9).

Next, the FFR calculator 109 calculates, with respect to each stenosedpart located on the inner wall of the responsible blood vessel specifiedby the responsible blood vessel specifying unit 108, a tissue blood flowvolume on a downstream side of each stenosed part and a tissue bloodflow volume on an upstream side of each stenosed part, based on thecolor map g3 generated by the cardiac muscle analysis unit 106. Then,the FFR calculator 109 calculates the FFR value at each locationincluding at least the stenosed part by dividing the calculated tissueblood flow volume on the downstream side of the stenosed part by thecalculated tissue blood flow volume on the upstream side of the stenosedpart (step S10).

Subsequently, the responsible stenosis specifying unit 110 specifies, asa responsible stenosis, a stenosed part at which the FFR valuecalculated by the FFR calculator 109 is less than a threshold value(step S11).

Thereafter, for example, as illustrated in FIG. 6 and FIG. 7, thedisplay unit 112 displays the markers generated by the marker generator111, which represent the responsible blood vessel, the responsiblestenosis and the FFR value, such that the markers are superimposed on athree-dimensional image g4 or a two-dimensional image g5, which isderived from the volume data (step S12).

The above-described embodiment is configured to include the heart regionextraction unit 105, cardiac muscle analysis unit 106 and coronaryartery analysis unit 107, which can extract the heart region, cardiacmuscle region, coronary artery and stenosed part from the volume data bythe CT apparatus 20; the responsible blood vessel specifying unit 108which specifies the responsible blood vessel, based on the processresult by the cardiac muscle analysis unit 106; the responsible stenosisspecifying unit 110 which specifies the responsible stenosis, based onthe process results by the coronary artery analysis unit 107,responsible blood vessel specifying unit 108 and FFR calculator 109; andthe display unit 112 which displays the markers relating to theresponsible blood vessel and responsible stenosis such that the markersare superimposed on the three-dimensional image or two-dimensionalimage, which is derived from the volume data. By this configuration, asillustrated in FIG. 6, the relationship in correspondency between theresponsible stenosis and the dominance territory can be visually shownto the doctor, and thus the possibility of a human error can be reduced.

Additionally, in the present embodiment, since the FFR calculator 109calculates FFR values on a simulation basis, that is, since nothinginvasive, such as a pressure wire, is used, the load on the patient at atime of examination can be reduced.

In the meantime, in the present embodiment, although images, which thedisplay unit 112 displays, are illustrated in FIG. 6 and FIG. 7 by wayof example, the images displayed on the display unit 112 are not limitedto these. For example, images g6 and g7 as illustrated in FIG. 8A andFIG. 8B may be displayed. FIG. 8A and FIG. 8B illustrate examples of theimages g6 and g7 in which the degrees of priority of treatment ofstenosed parts are ranked based on the FFR values calculated by the FFRcalculator 109, and this process result is superimposed as markers.Here, a marker (circle mark), which indicates a stenosed part with ahigher degree of priority of treatment, is larger. In addition, FIG. 8Aillustrates an example of the image g6, in which a bar graph indicativeof the analysis result of the plaque nature by the coronary arteryanalysis unit 107 is superimposed as a marker, in addition to the degreeof priority. Incidentally, in the image g6 illustrated in FIG. 8A, theproperties of blood, etc., in addition to the analysis result of theplaque nature, may be superimposed as markers. Besides, when a pluralityof responsible blood vessels exist, it is possible to display an imageon the display unit 112, such that the degrees of priority of treatmentof stenosed parts over the plural responsible blood vessels are ranked,and then the process result is superimposed as markers.

Additionally, according to the medical image processing apparatus 10relating to the embodiment, when the dominance map is referred to by theresponsible blood vessel specifying unit 108, it is possible to detectwhether a territory of another artery extends into a part of a territoryto which blood should be supplied by a certain artery, and to suggest apossibility of blood supply by a collateral vessel if such extension ofthe territory of the another artery is detected. In general, if acollateral vessel is present, the reliability of the FFR value lowers.Thus, for example, as illustrated in FIG. 9, by displaying on thedisplay unit 112 an image g8 which suggests the presence of thecollateral vessel, the possibility of a human error can further bereduced.

Furthermore, according to the medical image processing apparatus 10relating to the embodiment, after the responsible stenosis is specifiedby the responsible stenosis specifying unit 110, the diameter in crosssection and the length of the responsible stenosis can be measured fromthe two-dimensional image derived from the volume data, and the optimalsize of the catheter/stent can be suggested based on the measurementresult. Specifically, for example, as illustrated in FIG. 10, bydisplaying on the display unit 112 an image g9 which suggests theoptimal size of the catheter/stent, the possibility of a human error canfurther be reduced.

Additionally, according to the medical image processing apparatus 10relating to the embodiment, when the presence of ischemic regions atplural locations has been indicated by the cardiac muscle analysis unit106, the thickness of the cardiac muscle, etc. can be measured from thevolume data, and, based on the result of this measurement, such settingcan be added that a blood vessel corresponding to a dominance territoryof a necrosed cardiac muscle is not specified as a responsible bloodvessel.

Furthermore, according to the medical image processing apparatus 10relating to the embodiment, when a desired three-dimensional image wasdisplayed by the display unit 112, if an input indicating selection of aresponsible blood vessel or a responsible stenosis is accepted from aninput interface (not shown) such as a mouse, a keyboard or a touchpanel, it is also possible to automatically rotate the three-dimensionalimage at such an angle that the selected responsible blood vessel orresponsible stenosis can easily be observed.

Second Embodiment

FIG. 11 is a schematic view illustrating a configuration example of amedical image processing system including a medical image processingapparatus according to a second embodiment. A medical image processingsystem 1 illustrated in FIG. 11 is a system in which a medical imageprocessing apparatus 10, a CT (Computed Tomography) apparatus 20, an MRI(Magnetic Resonance Imaging) apparatus 30, a nuclear medicine diagnosisapparatus 40, and a PACS (Picture Archiving and Communication System) 50are communicably connected via a network 60 such as a LAN (Local AreaNetwork) or a public electronic communication network. Thus, the medicalimage processing apparatus 10 is provided with a communication interface103 which enables communication with the CT apparatus 20, MRI apparatus30, nuclear medicine diagnosis apparatus 40 and PACS 50.

As illustrated in FIG. 11, the medical image processing apparatus 10includes an image storage unit 101, a territory map storage unit 102,the communication interface 103, a controller 104, a heart regionextraction unit 105, a cardiac muscle analysis unit 106, a coronaryartery analysis unit 107, a responsible blood vessel specifying unit108, an FFR calculator 109, a marker generator 111, and a display unit111. Hereinafter, a description is given of only the structure which isdifferent from the medical image processing apparatus 1 illustrated inthe first embodiment.

The image storage unit 101 is a storage device which stores time-seriesthree-dimensional contrast-enhanced CT image data over a plurality oftime phases relating to a chest region including the heart of thesubject, as process images which are transmitted from the CT apparatus20 or PACS 50 under the controller 104.

The territory map storage unit 102 is a storage device which stores aterritory map which defines, as illustrated in FIG. 2, a relationshipbetween coronary arteries and dominance territories to which nutritionis supplied by the respective coronary arteries.

The heart region extraction unit 105 extracts a heart region from thevolume data by a heart contour extraction process or the like.

The cardiac muscle analysis unit 106 extracts a cardiac muscle regionfrom the heart region extracted by the heart region extraction unit 105,for example, by a threshold process by CT values corresponding to acontrast medium concentration. In addition, the cardiac muscle analysisunit 106 specifies a necrosed cardiac muscle region of the extractedcardiac muscle region, that is, a myocardial infarction region whichcontributes to myocardial infarction, by late gadolinium enhancement bythe MRI apparatus 30, saccharometabolism measurement by the nuclearmedicine diagnosis apparatus 40, etc.

Furthermore, the cardiac muscle analysis unit 106 executes cardiacmuscle perfusion analysis, that is, calculates the volume of a bloodflow moving during a period from flow-in to flow-out of a contrastmedium with respect to each pixel or each local part within theextracted cardiac muscle region. For example, in the photography usingthe CT apparatus 20, a non-ionic contrast medium is injected in thepatient, and perfusion information of an internal organ can be depictedfrom the variation of the CT value. Thus, in the CT perfusion analysis,a time-based variation of a CT image (volume data), which is composedof, for example, 512×512 pixels, is measured from a variation of the CTvalue at each pixel, and the blood flow volume, etc. can be numericallyexpressed. In this manner, one color map representing the perfusioninformation (e.g. blood flow volume) of the internal organ is generatedfrom the CT images of plural time phases.

Specifically, the cardiac muscle analysis unit 106 can specify not onlythe myocardial infarction region, but can also specify, for example, apart with a decreased blood flow, that is, an ischemic region, by athreshold process from a spatial distribution of the calculated bloodflow volume.

The coronary artery analysis unit 107 extracts a plurality of coronaryarteries from the heart region extracted by the heart region extractionunit 105, and further extracts at least one stenosed part from eachextracted coronary artery. Specifically, the coronary artery analysisunit 107 executes analysis of an anatomical structure of a coronaryartery and a plaque nature along a vessel center line of the coronaryartery, the inner wall of the blood vessel, etc., and extracts volumedata relating to the coronary artery, that is, extracts the coronaryartery and a stenosed part located on the inner wall of this coronaryartery. Incidentally, concrete examples of the plaque nature include alipid amount, a serum cholesterol concentration, hardness, the degree ofcalcification, and the thickness of a fibrous capsule (Thin-cap).

The responsible blood vessel specifying unit 108 refers to the dominancemap, which is stored in the territory map storage unit 102, for themyocardial infarction region specified by the cardiac muscle analysisunit 106, thereby specifying a blood vessel (hereinafter referred to as“infarction responsible blood vessel”) which is inherently responsiblefor supply of nutrition to the myocardial infarction region.

In the meantime, when the ischemic region, in place of the myocardialinfarction region, is specified by the cardiac muscle analysis unit 106,the responsible blood vessel specifying unit 108 refers to the dominancemap, which is stored in the territory map storage unit 102, for theischemic region specified by the cardiac muscle analysis unit 106,thereby specifying a blood vessel (hereinafter referred to as “ischemiaresponsible blood vessel”) which is inherently responsible for supply ofnutrition to the ischemic region.

The FFR calculator 109 calculates, on a simulation basis, FFR valuesrelating a plurality of locations including at least a stenosed part ofeach coronary artery extracted by the coronary artery analysis unit 107.Specifically, the FFR calculator 109 first calculates a tissue bloodflow volume at least at one location on a downstream side of thestenosed part in the coronary artery and a tissue blood flow volume atleast at one location on an upstream side of the stenosed part in thecoronary artery, based on the color map generated by the cardiac muscleanalysis unit 106. Then, the FFR calculator 109 calculates the FFR valueat each location including at least the stenosed part by dividing thecalculated tissue blood flow volume on the downstream side of thestenosed part by the calculated tissue blood flow volume on the upstreamside of the stenosed part. In the meantime, the description has beengiven here of the case of calculating the FFR value corresponding to onestenosed part in the coronary artery. However, for example, in the caseof calculating the FFR value of the entirety of the coronary artery, thetissue blood flow volume on the upstream side of the stenosed part,which is located on the most upstream side in the coronary artery may befixed as a reference value, and tissue blood flow volumes at otherplural locations may be set as variables (it is assumed that the FFRcalculator 109 has calculated the tissue blood flow volumes at plurallocations in the coronary artery). Thereby, the FFR calculator 109 cancalculate the FFR values corresponding to the plural locations, that is,the FFR values of the entirety of the coronary artery.

The marker generator 111 generates data of markers (marks) whichrepresent the infarction responsible blood vessel (or ischemiaresponsible blood vessel) specified by the responsible blood vesselspecifying unit 108, and the FFR values calculated by the FFR calculator109. These markers are displayed on the display unit 111 such that themarkers are superimposed on a three-dimensional image generated byrendering, etc. from the volume data, or a two-dimensional imagegenerated by cross-section conversion (Multi-Planar Reconstruction).Incidentally, the image, on which the markers generated by the markergenerator 111 are superimposed, is not limited to the image derived fromthe volume data by the CT apparatus 20, but may be an image acquiredfrom other modality such as an X-ray diagnosis apparatus.

Referring now to schematic views of FIG. 2, and FIG. 13 to FIG. 16, anda flowchart of FIG. 12, a description is given of an example of theoperation of the medical image processing apparatus 10 according to thepresent embodiment.

Here, it is assumed, however, that the time-series volume data over aplurality of time phases relating to the chest region from the CTapparatus 20 or PACS 50 is prestored in the image storage unit 101. Inaddition, it is assumed that the heart region extraction unit 105 hasalready read out, under the controller 104, volume data of a specifictime phase with a relatively small beat, as a process image, from theimage storage unit 101, and has already extracted a heart region fromthe volume data.

To start with, the coronary artery analysis unit 107 executes a coronaryartery analysis process on a target that is the heart region extractedby the heart region extraction unit 105 (step S21). Specifically, thecoronary artery analysis unit 107 executes analysis of an anatomicalstructure of a coronary artery and a plaque nature along a vessel centerline of the coronary artery, the inner wall of the blood vessel, etc.,and extracts the coronary artery and a stenosed part located on theinner wall of this coronary artery.

Subsequently, the cardiac muscle analysis unit 106 extracts a cardiacmuscle region from the heart region extracted by the heart regionextraction unit 105, by a threshold process by CT values correspondingto a contrast medium concentration. Thereafter, the cardiac muscleanalysis unit 106 specifies a necrosed cardiac muscle region of theextracted cardiac muscle region, that is, a myocardial infarction regionwhich contributes to myocardial infarction, by late gadoliniumenhancement by the MRI apparatus 30, saccharometabolism measurement bythe nuclear medicine diagnosis apparatus 40, etc. (step S22, S23, S24).

Next, the responsible blood vessel specifying unit 108 refers to thedominance map, which is stored in the territory map storage unit 102,for the myocardial infarction region specified by the cardiac muscleanalysis unit 106, thereby specifying an infarction responsible bloodvessel from each coronary artery extracted by the coronary arteryanalysis unit 107 (step S25).

Subsequently, the marker generator 111 generates data of a marker whichrepresents the infarction responsible blood vessel specified by theresponsible blood vessel specifying unit 108 (step S26). Specifically,for example, as illustrated in FIG. 13, the marker generator 111generates a marker m1 representing a contour of the infarctionresponsible blood vessel.

Next, the FFR calculator 109 calculates the FFR values corresponding tothe entirety of the coronary artery with respect to each coronary arteryextracted by the coronary artery analysis unit 107 (step S27).

Subsequently, the marker generator 111 generates a marker whichrepresents the FFR value corresponding to each coronary artery, whichwas calculated by the FFR calculator 109 (step S28). Specifically, forexample, as illustrated in FIG. 14, the marker generator 111 generates amarker m2 which represents a transition of the FFR value of eachcoronary artery.

Thereafter, for example, as illustrated in FIG. 15, the display unit 111displays the marker m1 representing the infarction responsible bloodvessel and the marker m2 representing the transition of the FFR value ofeach coronary artery, which were generated by the marker generator 111,such that the marker m1 and marker m2 are superimposed on atwo-dimensional image g1 which was derived from the volume data (stepS29). Incidentally, the image, which the display unit 111 displays, isnot limited to the two-dimensional image g1, but may be an image onwhich the markers are superimposed on a three-dimensional image g2 whichwas derived from the volume data, for example, as illustrated in FIG.16, or an image acquired from other modality.

In the meantime, in the above description of the example of theoperation, the case was described in which the responsible blood vesselspecifying unit 108 specifies the infarction responsible blood vessel.However, for example, as illustrated in a flowchart of FIG. 17, also inthe case in which the responsible blood vessel specifying unit 108specifies the ischemia responsible blood vessel, the operation is thesame as in the above example, except that the medical image processingapparatus 10 specifies the ischemic region by a cardiac muscle perfusionanalysis by the CT apparatus 20 or MRI apparatus 30, a SPECT examinationby the nuclear medicine diagnosis apparatus 40, etc. (step S22′, S23′,S24′), specifies the ischemia responsible blood vessel from thespecified ischemic region (step S25′), and generates a markerrepresenting the specified ischemia responsible blood vessel (step 26′).

The above-described second embodiment is configured to include the heartregion extraction unit 105, cardiac muscle analysis unit 106 andcoronary artery analysis unit 107, which can extract the heart region,cardiac muscle region, coronary artery, stenosed part and myocardialinfarction region from the volume data by the CT apparatus 20; theresponsible blood vessel specifying unit 108 which specifies theinfarction responsible blood vessel, based on the process result by thecardiac muscle analysis unit 106; and the display unit 111 whichdisplays the markers representing the infarction responsible bloodvessel and the FFR value calculated by the FFR calculator 109, such thatthe markers are superimposed on the two-dimensional image orthree-dimensional image, which is derived from the volume data. By thisconfiguration, it is possible to show the doctor that the reliability ofthe FFR value of the part, on which the marker representing theinfarction responsible blood vessel is displayed by superimposition, islow.

Additionally, in the present embodiment, since the FFR calculator 109calculates FFR values on a simulation basis, that is, since nothinginvasive, such as a pressure wire, is used, the load on the patient at atime of examination can be reduced.

Third Embodiment

Next, a medical image processing apparatus according to a thirdembodiment is described with referenced to the above-described FIG. 11.In the present embodiment, a function of determining whether a stenosedpart in a coronary artery is a treatment-target stenosis or anon-treatment-target stenosis is added to the medical image processingapparatus 10 illustrated in the second embodiment. Incidentally, onlyfunctions different from the second embodiment will be described withreference to a flowchart of FIG. 18 and a schematic view of FIG. 19.Specifically, since the process of steps S21 to S28 is the same as inthe above-described second embodiment, a detailed description thereof isomitted here, and the process of steps S30 to S36 will mainly bedescribed below.

The coronary artery analysis unit 107 determines, with respect to eachstenosed part extracted in the process of step S21, whether the stenosedpart is a stenosis located in the infarction responsible blood vessel(step S30).

If the result of determination by the process of step S30 indicates thatthe stenosed part is a stenosis located in the infarction responsibleblood vessel (Yes in step S30), the cardiac muscle analysis unit 106determines whether a surviving cardiac muscle is present in themyocardial infarction region specified in the process of step S24 (stepS31). Specifically, the cardiac muscle analysis unit 106 determineswhether the myocardial infarction region reaches half the thickness ofthe cardiac muscle, from the late gadolinium enhancement by the MRIapparatus 30, etc. If the result of the determination indicates that themyocardial infarction region reaches half the thickness of the cardiacmuscle, it is deemed that a surviving cardiac muscle is absent. If theresult of the determination indicates “NO”, it is deemed that asurviving cardiac muscle is present. Incidentally, if the result of thedetermination by the process of step S31 indicates “NO” (No in stepS31), the process goes to step S35 which is to be described later.

If the result of the determination by the process of step S31 indicatesthat a surviving cardiac muscle is present (Yes in step S31), the markergenerator 111 generates a marker representing the infarction responsibleblood vessel in which the surviving cardia muscle is present, and amarker representing a treatment-target stenosis (step S32).Specifically, for example, as illustrated in FIG. 19, the markergenerator 111 generates a marker m3 representing the contour of theinfarction responsible blood vessel in which the surviving cardia muscleis present, and a marker m4 representing the treatment-target stenosis.

Here, if the result of the determination by the process of step S30indicates “NO” (No in step S30), the coronary artery analysis unit 107determines whether the FFR value corresponding to the stenosed part,among the FFR values of the respective coronary arteries calculated inthe process of step S27, is a threshold value or less (step S33).

If the result of the determination by the process of step S33 indicatesthat the FFR value corresponding to the stenosed part is the thresholdvalue or less (Yes in step S33), the marker generator 111 generates amarker representing a treatment-target stenosis (step S34).Specifically, the marker generator 111 generates a marker correspondingto the marker m4 illustrated in FIG. 19.

If the result of the determination by the process of step S33 indicates“NO” (No in step S33), the marker generator 111 generates a markerrepresenting a non-treatment-target stenosis (step S35). Specifically,for example, as illustrated in FIG. 19, the marker generator 111generates a marker m5 representing a non-treatment-target stenosis.

Thereafter, the display unit 111 displays the marker m1 representing theinfarction responsible blood vessel, the marker m2 representing thetransition of the FFR value of each coronary artery, the marker m3representing the infarction responsible blood vessel in which thesurviving cardia muscle is present, and the marker m4 representing thetreatment-target stenosis, which were generated by the marker generator111, such that these markers are superimposed on the three-dimensionalimage g3 which was derived from the volume data (step S36).Incidentally, the image, which the display unit 111 displays, is notlimited to the three-dimensional image g3, but may be an image on whichthe markers are superimposed on a two-dimensional image derived from thevolume data, or an image acquired from other modality. In addition, whenthe marker m1 representing the infarction responsible blood vessel, andthe marker m3 representing the infarction responsible blood vessel inwhich the surviving cardia muscle is present, are superimposed at thesame position on the image, it is assumed the marker m3 ispreferentially displayed.

The above-described third embodiment is configured to include thecardiac muscle analysis unit 106 and coronary artery analysis unit 107,which determine whether a surviving cardiac muscle is present in themyocardial infarction region, and whether the stenosed part in thecoronary artery is a treatment-target stenosis or a non-treatment-targetstenosis; and the display unit 111 which displays the markerrepresenting the infarction responsible blood vessel in which thesurviving cardia muscle is present, the marker representing thetreatment-target stenosis and the marker representing thenon-treatment-target stenosis, such that these markers are superimposedon the three-dimensional image or two-dimensional image which wasderived from the volume data. By this configuration, compared to thefirst embodiment, a greater amount of information can be presented tothe doctor.

According to at least one of the above-described second and thirdembodiments, it is possible to show the doctor that the reliability ofthe FFR value is low, whether a surviving cardiac muscle is present ornot, and whether a stenosed part is a stenosis which is suitable fortreatment or not. Therefore, the possibility of a human error can bereduced.

The above described “processing circuitry” means, for example, a centralprocessing unit (CPU), a graphics processing unit (GPU), an applicationspecific integrated circuit (ASIC), a programmable logical device (e.g.,a simple programmable logic device (SPLD), a complex programmable logicdevice (CPLD), and a field programmable gate array (FPGA)), or the like.

Note that programs may be directly incorporated in processing circuitryinstead that programs are stored in storage memory 12. In this case, theprocessing circuitry reads programs incorporated in circuitry andexecutes the programs to realize predetermined functions.

Each function (each component) in the present embodiment is notnecessary to be corresponded to a single processing circuit and may berealized by a plurality of processing circuits. To the contrary, forexample, at least two functions (at least two components) may berealized by a single processing circuit. Further, a plurality offunctions (a plurality of components) may be realized by a singleprocessing circuit.

While certain embodiments of the invention have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the invention. Indeed, the novelembodiments described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the embodiments described herein may be made without departingfrom the spirit of the inventions. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

REFERENCE SIGNS LIST

What is claimed is:
 1. A medical image processing apparatus comprising:a first extraction unit implemented by processing circuitry configuredto extract a plurality of coronary arteries depicted in data of imagesof a plurality of time phases relating to the heart, and to extract atleast one stenosed part depicted in each of the extracted coronaryarteries; a calculation unit implemented by processing circuitryconfigured to calculate a pressure gradient of each of the extractedcoronary arteries, based on tissue blood flow volumes of the pluralityof extracted coronary arteries; a second extraction unit implemented byprocessing circuitry configured to extract an ischemic region depictedin the images; a specifying unit implemented by processing circuitryconfigured to specify a responsible blood vessel of the ischemic regionby referring to a dominance map, in which each of the extracted coronaryarteries and a dominance territory are associated, for the extractedischemic region, and to specify a responsible stenosis, based on thepressure gradient corresponding to a stenosed part in the specifiedresponsible blood vessel; and a display configured to display an imagein which the specified responsible stenosis is depicted, together withinformation indicative of the responsible stenosis.
 2. The medical imageprocessing apparatus of claim 1, wherein the display unit is configuredto display the image in which the specified responsible stenosis isdepicted, together with a pressure gradient corresponding to theresponsible stenosis.
 3. The medical image processing apparatus of claim1, wherein the display unit is configured to display the image in whichthe specified responsible blood vessel is depicted, together withinformation indicative of the responsible blood vessel.
 4. The medicalimage processing apparatus of claim 1, wherein the specifying unit isconfigured to refer to the dominance map for the extracted ischemicregion, thereby specifying whether a collateral vessel is present in theischemic region, and the display control unit is configured to effectdisplay of information indicating whether a collateral vessel is presentin the ischemic region.
 5. The medical image processing apparatus ofclaim 1, wherein the extraction unit is configured to generate a tissueblood flow image relating to a cardiac muscle from the images, and toextract the ischemic region from the tissue blood flow image.
 6. Themedical image processing apparatus of claim 1, further comprising apriority order determination unit implemented by processing circuitryconfigured to rank a degree of priority of treatment of a stenosed part,based on the pressure gradient corresponding to the stenosed part in thespecified responsible blood vessel, and the display unit is configuredto display information indicative of the degree of priority of treatmentwhich is determined.
 7. The medical image processing apparatus of claim1, wherein the second extraction unit is configured to extract amyocardial infarction region from the ischemic region, the specifyingunit is configured to refer to the dominance map for the extractedmyocardial infarction region, thereby specifying a responsible bloodvessel of the myocardial infarction region from each of the coronaryarteries, and the display displays an image in which the specifiedresponsible blood vessel is depicted, together with informationindicative of the responsible blood vessel.
 8. The medical imageprocessing apparatus of claim 1, wherein the specifying unit isconfigured to specify at least one of a catheter and a stent for use intreatment of the responsible stenosis, based on a size of the specifiedresponsible stenosis, and the display unit is configured to display theat least specified one of the catheter and the stent.
 9. The medicalimage processing apparatus of claim 1, wherein the display displays theimage such that the image is rotated in accordance with a position ofthe specified responsible stenosis.
 10. A medical image processingmethod comprising: extracting a plurality of coronary arteries depictedin data of images of a plurality of time phases relating to the heart,and to extract at least one stenosed part depicted in each of theextracted coronary arteries; calculating a pressure gradient of each ofthe extracted coronary arteries, based on tissue blood flow volumes ofthe plurality of extracted coronary arteries; extracting an ischemicregion depicted in the images; specifying a responsible blood vessel ofthe ischemic region by referring to a dominance map, in which each ofthe extracted coronary arteries and a dominance territory areassociated, for the extracted ischemic region, and to specify aresponsible stenosis, based on the pressure gradient corresponding to astenosed part in the specified responsible blood vessel; and displayingan image in which the specified responsible stenosis is depicted,together with information indicative of the responsible stenosis.